Burner control apparatus



United States Patent 01 hoe 3,395,968 Patented Aug. 6, 1968 3,395,968BURNER CONTROL APPARATUS John W. Mobarry, Edina, and James S. Warren,Minuetonka, Minn., assignors to Honeywell Inc., Minneapolis, Minn., acorporation of Delaware Filed Feb. 13, 1967, Ser. No. 615,399 8 Claims.(Cl. 431-45) ABSTRACT OF THE DISQLOSURE open switch of the relay.

Background of the invention Non-recycle burner control apparatus areknown, as are burner control apparatus having timed ignition utilizing abimetal ignition timer. Our invention relates to an improvement in thefield of such burner control apparatus.

Summary of the invention Our invention provides non-recycle and timedignition operation of a burner unit by means of electrical circuitrywhich includes a safety lockout timer having an actuator, a flamedetector, an ignition timer having an actuator, and a burner controlrelay having a winding. More speclfically, the initial energizingcircuit for the relay winding includes in series the safety lockoutactuator, a switch controlled by the flame detector, and the timeractuator. Upon energization of the relay, a single normally-open switchof the relay is effective to establish two maintaining circuits, one ofwhich includes in a series circuit the safety lockout actuator and theswitch controlled by the flame detector, and the other of which includesin a series circuit the timer actuator and the relay winding.

Brief description of the drawing FIGURE 1 discloses a preferredembodiment of our invention, connected to control a gas burner unit,

FIGURE 2 is a partial circuit diagram of the embodiment of FIGURE 1,showing the circuit which includes the safety lockout device actuator,the ignition timing device actuator and the relay winding, and

FIGURE 3 is a partial circuit diagram showing the circuit of FIGURE 1connected to control an oil burner unit.

Description of the preferred embodiments Referring to FIGURE 1,reference numeral identifies a burner unit having a main burner 11 witha fuel valve 12, a pilot burner 13 with a fuel valve 14, and ignitionmeans with an ignition electrode 16.

Our invention provides non-recycling control and timed ignition controlof burner unit 10. Reference numeral 18 designates a controller in theform of a bimetal thermostat having a normally-open switch. Controller18 is adapted to be located in the area to be heated by operation ofburner unit 10. Upon closing of controller 18, valve 14 and ignitionmeans 15 are energized to establish flame at pilot burner 13. Thepresence of flame at the pilot burner is detected by a flame detector19, which includes a flame rod 17, causing a flame relay to beenergized. Energization of flame relay 20 is effective to energize mainvalve 12. Flame rod 17 is situated to be subjected to flame at bothpilot burner 13 and main burner 11. Flame relay 20 is deenergized uponthe absence of flame at the pilot burner and the main burner. Ignitionmeans 15 is deenergized a time period after initial energization ofvalve 14 and ignition means 15.

Reference numeral 21 identifies a burner control relay having a winding22, and normally open switches 23, 24 and 25. Reference numeral 26identifies a bimetal safety lockout timer having a normally-closedswitch 27, a bimetal operator 28, and an actuator in the form of heater29. Safety lockout timer 26 provides a period of time delay from initialenergization of the heater 29 to the opening of switch 27. Also, lockouttimer 26 requires manual reset, as by operation of reset button 30.Reference numeral 31 identifies timing means in the form of an ignitiontiming means having a normally closed ignition cutoff switch 32, abimetal operator 33, and an actuator in the form of a heater 34. Timer31 provides a period of time delay, greater than the time delay oflockout timer 26, from initial energization of heater 34 to the openingof switch 32. Timing means 31 is held in its actuated position (switch32 open) by continued energization of heater 34 and automatically resetsupon cooling of bimetal 33.

Operating voltage for the apparatus of FIGURE 1 is derived from a sourceof AC voltage, not shown, to which power line conductors 35 and 36 areadapted to be connected. Conductors 35 and 36 are connected to theprimary winding of step-down transformer 37. The secondary winding oftransformer 37 includes terminals 38, 39 and 40. Terminals 38 and 39constitute a first voltage source and terminals 39 and 4t} constitute asecond voltage source, the two voltage sources being in voltage addingor aiding relation between terminals 38 and 40.

Considering the operation of the apparatus of FIGURE 1, the apparatus isshown in the standby condition Wherein controller 18 is in an opencondition, indicating no need for operation of burner unit 10. Upon aneed for operation of the burner unit, controller 18 closes itsnormallyopen switch and an energizing circuit for the winding of relay21 can be traced from terminal 38 through heater 29, normally-closedswitch 50 of flame relay 20, thermistor 51, controller 18, winding 22,heater 34, and switch 27 to terminal 40. From this circuit it can beseen that the following conditions must prevail in order for relayWinding 22 to be energized: heater 29 must have electrical continuity,flame relay 21 must be in a condition indicating no-fiame, heater 34must have electrical continuity.

Thermistor 51 functions to provide a short period of time delay forpull-in of relay 21. When thermistor S1 is cool, the current through thewinding of relay 21 is lim ited to below the pull-in value. Asthermistor S1 selfheats, its resistance drops and relay 21 pulls-in.

Upon pull-in of relay 21, switches 23, 24, and 25 close. The closing ofswitch 23 is effective to energize valve 14 and ignition means 15. Thecircuit can be traced from power line conductor 36 through switch 23,switch 32, and ignition means 15 and valve 14 in parallel to power lineconductor 35.

The closing of switch 25 provides a shunt circuit around the now hotthermistor 51, allowing the thermistor to cool.

The closing of switch 24 completes two maintaining circuits, one forheater 29 of safety lockout device 26 until switch 50 opens, and theother for winding 22 and heater 34 of time 31 and to maintain theseelements energized after switch 50 opens. The first circuit can betraced from terminal 38 through heater 29, switch 50, switch 25, andswitch 24 to terminal 39. From this first circuit it can be seen thatheater 29 is maintained energized until flame is detected at pilotburner 13 and switch 50 opens. The second circuit can be traced fromterminal 40 through switch 27, heater 34, winding 22,

controller 18 and switch 24- to terminal 39. From this second circuit itcan be seen that heater 34 and winding 22 are maintained energized solong as there is a need for operation of the burner unit.

In accordance with the teachings of our invention, electrical continuityof heater 34 is continuously checked during the entire period ofoperation of the burner. Should the heater of timing means 31malfunction by open-circuit, the winding of relay 21 is deenergized andits switches open to deenergize burner unit It). Thus, since initialenergization of relay winding 22 depends upon continuity of both heaters29 and 34, and since continued maintaining energization of winding 22depends upon continuity of heater 34, our invention provides a simple,low cost and reliable control providing non-recycle and timed ignitionof a burner unit.

Upon establishment of flame at pilot burner 13, flame detector 19energizes flame relay 20, actuating switches 50 and 60. Theopening ofswitch 50 deenergizes heater 29 of safety lockout means 26, as abovedescribed. The closing of switch 60 is effective to energize valve 12through a circuit which can be traced from power line conductor 36,switch 23, switch 60 and valve 12 to power line conductor 35. Normally,flame is established at pilot burner 13 immediately after energizationof valve 14 and ignition means 15. Thus, there is a period in which bothpilot flame and main flame exists. After the timing of timing means 31iscompleted, switch 32 opens to deenergize valve 14 and ignition means15.

Should a flame failure now occur at main burner 11, flame relay isdeenergized to open switch 60 and close switch 50. The opening of switch60 deenergizes valve 12. The closing of switch operatively energizesheater 29 of safety lockout means 26 and, after the timing period ofthis device has been accomplished, switch 27 opens to deenergize relaywinding 22. Since lockout device 26 requires manual operation, thedevice is now in safety lockout condition. It is necessary to manuallyactuate reset button 30 to reset the control.

In FIGURE 3 we show our invention connected to control an oil burnerunit having an oil burner 90 and ignition means 91. In this embodiment,relay 21 of FIGURE 1 and its switch 23 is effective to energize oilburner 90 and ignition means 91. Timer 31 of FIGURE 1 is effective,after a time period, to open switch 32 to deenergize ignition means 91.Switch of flame relay 20, FIGURE 1, is eliminated, While the remainingstructure of FIGURE 1 is used with the embodiment of FIG- URE 3.

The embodiments of the invention in which an exclusive property or rightis claimed are defined as follows:

1. Control apparatus for use with a condition chang ing installationhaving an initiating means, comprising:

a condition changing control relay having a winding and a first normallyopen switch, time delayed safety lockout means having an actuator,initiating 'means time delayed timing means having an actuator, saidtiming means having a period of time delay greater than the time delayof said safety lockout means,

condition detecting means for detecting a condition established at thecondition changing installation by operation of the initiating means,said detecting means having a normally closed switch,

a voltage source having first, second and third terminals,

first circuit means connecting said lockout means actuator, saiddetecting means switch, and said relay switch in a series circuit fromsaid first terminal to said second terminal,

and second circuit means connecting said timing means actuator, saidrelay winding, and said relay switch in a series circuit from said thirdterminal to said second terminal. I

2. The control apparatus of claim 1, for use with a fuel burnerinstallation having ignition means, wherein said control relay is aburner control relay, wherein said timing means is an ignition timingmeans having a period of time delay greater than the time delay of saidsafety lockout means, wherein said detecting means is a flame detectingmeans, and including first voltage source means connected from saidfirst terminal to said second terminal, and second voltage source meansconnected from said second terminal to said third terminal, said firstand second voltage source means being connected in aiding relationbetween said first and third terminals.

3. The control apparatus of claim 2 including circuit means controlledby said relay and said ignition timing means and adapted to be connectedto the ignition means to energize the ignition means for a time periodbeginning with initial energization of said relay winding andterminating at the end of the period of time delay of said timing means.

4. The control apparatus of claim 3, wherein said safety lockout meansincludes a normally closed switch connected to interrupt energization ofsaid relay winding upon opening of said switch, and said timing meansincludes a normally closed switch to interrupt energization of theignition means at the end of the period of time delay of said timingmeans. a

5. The control apparatus of claim 3, wherein said safety lockout meansincludes a normally closed safety switch connected in series with saidsecond circuit means.

6. The control apparatus of claim 5, wherein said timing means includesa normally closed ignition cutoff switch which opens at the end of theperiod of time delay of said timing means.

7. The control apparatus of claim 1, for use with a fuel burnerinstallation having ignition means, and having a main valve to controlthe flow of fuel to a main burner; wherein said timing means is anignition timing means, wherein said detecting means is a flame detectingmeans adapted to detect flame at the main burner, and including firstvoltage source means connected from said first terminal to said secondterminal and second voltage source means connected from said secondterminal to said third terminal, said first and second voltage sourcemeans being connected in aiding relation between said first and thirdterminals.

8. The control apparatus of claim 7, for use with a fuel burnerinstallation wherein the ignition means includes a pilot valve tocontrol the flow of fuel to a pilot burner and means to ignite fuel atthe pilot burner, and wherein said flame detecting means is adapted todetect flame at the pilot burner and the main burner; and includingcircuit means controlled by said relay and said ignition timing meansand adapted to be connected to the ignition means to energize the pilotvalve and the means to ignite fuel at the pilot burner for a time periodbeginning with initial energization of said relay winding andterminating at the end of the period of time delay of said timing means,a normally closed switch controlled by said safety lockout means andconnected to interrupt energization of said relay winding upon openingof said switch, and circuit means controlled by said relay and saidflame detector and adapted to be connected to the main valve to energizethe main valve upon detection of flame at the pilot burner.

References Cited UNITED STATES PATENTS 3,270,799 9/1966 Pinckaers 158l283,270,800 9/1966 Deziel et a1. 158128 3,343,585 9/1967 Eckelberry 158128X FREDERICK L. MATTESON, IR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

